The control of the enzymatic synthesis of bile acid conjugates is being studied by a variety of approaches including subcellular localization of the enzymatic reactions, kinetic analysis of the substrate and product interactions and comparison of species known to have differences in the predominant amino acids conjugated. Purification of the enzymes catalyzing these reactions will also be accomplished. The effect of pharmacologic and physiologic pertubations will be studied in vitro and in vivo to elucidate potential mechanisms of the control of bile acid conjugation.